As seen in the video on page 4, a sloshing damper reduces the sway of tall buildings using a liquid. It works because the liquid has space to slosh (move back and forth) in response to the building’s movement. It is one example of a tuned mass damper—a device that helps to stabilize a structure by using mass that moves in response to a structure’s motion. The mass, in this case water, can be adjusted (or tuned) to optimize the effectiveness of the device.
When the building moves one direction, the liquid sloshes in the other direction. The movement of the water counteracts the motion of the building caused by the wind, reducing the amount of sway.
A variety of measurements (such as acceleration, velocity, and displacement) can be used to characterize the vibration or motion of the building. However, acceleration is a more direct and useful measurement for assessing human comfort.
Watch this video to see engineers test how well the solution is working.
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frequency - the rate of vibration. Every building has a structural frequency (also known as natural frequency or resonant frequency): a rate at which it vibrates, moves back and forth per unit time, when it is disturbed.
accelerometer - a device that measures acceleration (the rate of change in speed or direction) to detect motion.
g - a unit of measurement for acceleration. One g equals the acceleration due to Earth’s gravity at Earth’s surface. One milli-g is 1/1000 of a g (it is used to measure small changes in motion).